If you don’t have Western Electric transformers, you can pick up easy-to-wire isolation transformer boards from Newman-Kees RF Measurements & Engineering, as shown here:
This Audio Hum and Lightning Isolator board from Newman-Kees uses high-quality transformers to isolate lines.
This Audio Hum and Lightning Isolator board from Newman-Kees uses high-quality transformers to isolate lines.

They provide lightning isolation to 1200 Volts and can be strapped for various applications as shown in the schematic. Features include 600 Ohms in and out, primary and secondary center taps, board traces for attenuators and 1/8-inch mounting holes. Cost: $35.50. Email newman-kees-hertel-rf-eng@twc.com.